1. Field of the Invention
The present apparatus pertains generally to fluid control valves such as might commonly be found in water control or gas canisters, and specifically to indicator devices which signal the on or off state of the valve.
2. Description of the Related Art
Valves used to control the movement of fluids often times exist in an environment where it is not possible to view the fluid to determine motion of that fluid. This might occur in a water main where by the location of the main underground no sighting of water flow is possible from above ground. Another similar situation arises in the case of pressurized gas canisters due to potential transparency and lack of odor of the gas. In the particular case of the pressurized gas canister, even if a downstream valve is closed, the gas may still seep through. A resultant slow leak may pose health hazards dependent upon the gas type. The slow leak will also prove annoying and expensive in the replacement cost of the gas.
Several systems have been devised to indicate to a viewer or listener that a valve has undesirably been left in the open or on position. One system is disclosed by Furtney in U.S. Pat. No. 2,015,398. Furtney discloses a waterglass valve which, when in the off position, prominently displays a "differently" colored "shut" sign. The Furtney system requires that the valve be designed to accomodate the "shut" flag, and will not operate as a retrofit. Further, the Furtney valve would have to be substantially redisigned to be of any use on a system different than the boiler type system for which it was designed.
Another system is shown by Haws in U.S. Pat. No. 4,665,386. Haws discloses an electromechanical annunciating device. The device readily attaches to a pressurized gas canister at the valve. When rotated in the opening direction, a timer starts and will activate a bell if the valve is not closed. While the Haws system is readily retrofitted to any type of hand actuated valve, the operation and effectiveness of the device is questionable. If an explosive gas were to be left on and unattended for some reason, the activation of the device could cause a dangerous explosion. Additionally, if a user of the tank finishes hurriedly and leaves, the annunciater will ring without anyone being around to hear it. Then the user will not only have to replace the gas, but also the batteries.